QGIS Create a TIN: Difference between revisions
Content deleted Content added
No edit summary |
No edit summary |
||
Line 79:
<li>The resulting layer, called '''Draped''' will appear in the QGIS Layers panel. Right click '''Draped''' and select 'Rename Layer'. Rename the layer to '''Draped_Lines'''.
</ol>
==Create TIN Mesh==
Create a TIN Mesh using the QGIS processing tool 'TIN Mesh Creation'. This tool will generate a TIN mesh from the above outputs and any elevation points that are not snapped to the merge polygon. For more information about this tool, please refer to <u>[https://docs.qgis.org/3.34/en/docs/user_manual/processing_algs/qgis/mesh.html#tin-mesh-creation QGIS Documentation - TIN Mesh Creation]</u>.
<ol>
<li>Go to 'Mesh' in the processing tool list and select 'TIN Mesh Creation'. This opens the dialog shown below:
*Vector Layer: '''Draped_Lines'''
*Value on Vertex: Leave as default and tick on 'Use Z-coordinate for Value on Vertex'.
*Click [[File: QGIS_3D_Animation_add_keyframe_button_01.png|30px]] to add the vector layer to the table. Repeat the above two points for '''Draped_Polygon'''.
:*If there are any points layers within the merge polygon's extent but not snapped to the polygon, add these as well. For 'Value on Vertex', select the field that contains the elevation data (e.g. '''Z''').
*Output format: 2DM
*Output coordinate system: Use the project CRS.
*Output file: Save to the model's '''grid''' folder ('''TUFLOW\model\grid''').
<li>Click 'Run'. Once the tool is finished, click 'Close'. <br>
<br>
[[File: QGIS_Create_TIN_Create_Mesh_01a.png]]<br>
<br>
<li>The resulting layer will appear in the QGIS Layers panel.
<li>To view the triangular mesh, right click the TIN Mesh and select 'Properties'.
<li>In the 'Symbology' tab, select 'Rendering' from the top options and tick on 'Triangular Mesh Rendering'. Click 'OK'. <br>
<br>
[[File:QGIS_Create_TIN_Create_Mesh_02.png]]<br>
<br>
</ol>
==Update TUFLOW Geometry Control File (TGC)==
The TUFLOW Geometry Control File (.tgc) must be updated to reference the TIN Mesh, which will replace any topography-modifying GIS layers (Z shapes) within the mesh extent.
Remove all references to Z shapes (<tt><font color="blue">Read GIS Z Shape</font><font color="red"> ==</font></tt> ) in the TGC file and replace them with:<br>
<tt><font color="blue">Read TIN Zpts</font><font color="red"> ==</font> grid\<TIN_Mesh_filename>.2dm | gis\<merge_polygon_filename></tt>
For example:
=Conclusion=
| |||